Method of reducing microbial growth during processing of animal carcasses

ABSTRACT

Various food processing methods and a food processing system minimize microbial growth while an animal, such as a chicken, is processed into food. During processing, temperature of an animal carcass and atmosphere surrounding the carcass are controlled by spraying gases and a mixture of ozone and water on the carcass, directing the gases through a passage in a wall to cool a processing area, and flowing the gases into atmosphere surrounding the carcass. Preferably, the gases include ozone and cryogenic gases recycled from a cryogenic freezer. The system uses a reduced amount of fresh water by recycling water used during food processing.

This is a divisional of application Ser. No. 09/232.822, filed Jan. 19,1999 now U.S. Pat. No. 6,167,709, which is a divisional of applicationSer. No. 08/711.779, filed Sep. 10, 1996 (now U.S. Pat. No. 5,879,732).Each of these prior applications is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a food processing method and system.More particularly, the present invention relates to a method and systemfor minimizing microbial growth while an animal is processed into food.In addition, the present invention relates to controlling temperatureand reducing the need for fresh water during food processing.

2. Description of Related Art

The health conscious public demands food that is safe, sanitary, andfree of microorganisms and chemicals. In addition, government health andsafety agencies regulate the quality of food. Although the food industryattempts to meet the demands of both the public and the government,large scale food preparing operations inevitably provide environmentsfavorable for the growth of harmful bacteria, fungi, and othermicroorganisms.

Large facilities for processing live animals into food have been in usefor a number of years. Many of these facilities, however, lack adequateequipment and controls to reduce the growth of potentially harmfulmicroorganisms. Lack of sufficient cooling, atmosphere control, andcleansing are some of the primary reasons microbes thrive during foodprocessing.

In most conventional food processing facilities, an animal carcass iscooled only after the carcass is processed to remove viscera and cutinto portions. (As used herein, the term “carcass” generally means awhole animal body or a portion of the animal body) Immediately after ananimal is slaughtered, however, the resulting carcass is at atemperature that is approximately the same as the body temperature ofthe animal. This warm temperature of the carcass promotes microbialgrowth up until the time when the carcass is finally cooled. Because agreat amount of time normally passes from when an animal is slaughteredto when the processed carcass is cooled, significant growth of microbescan occur.

The atmosphere within a food processing facility also affects microbialgrowth during food processing. Many different types of microorganismsthrive on gases such as oxygen, but little or no attempt is made tocontrol the relative amounts of these gases during food processing. Inaddition, many of the existing food processing facilities do not usegases, such as ozone, nitrogen, carbon dioxide, and argon, which cancontrol microbial growth without contaminating the resulting food.

Poor cleaning of both animals and processing machines is yet anotherreason for microbial contamination. Typically, animals, such aschickens, are shipped to a food processing facility and slaughteredbefore they have been washed. The filth, fecal matter, and dirt carriedby these animals often spread throughout an entire food processingfacility, resulting in contaminated food.

As machines process one animal carcass after another, they often crosscontaminate carcasses and assist in spreading microbes. Fresh water orwater in combination with chemicals is used to wash the machines, butthe water alone is ineffective for killing microbes, and the chemicalsadded to water often pollute the water to a level requiring specialdisposal procedures. Because most conventional food processingfacilities use a significant amount of fresh water, they cannot belocated in areas lacking a large source of fresh water.

In light of the foregoing, there is a need in the art for a method andsystem for processing food to reduce microbial growth and to eliminatethe need for excessive amounts of fresh water.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a method and systemfor processing a live animals into food so that microbial growth isminimized.

In addition, the invention is directed to a method and system for animalprocessing without the need for an excessive amount of fresh water.

To achieve these and other advantages and in accordance with the purposeof the invention, as embodied and broadly described herein, theinvention includes a food processing method comprising the steps ofslaughtering an animal to produce a carcass, conveying the carcass to aprocessing area, processing the carcass in the processing area toconvert the carcass into food, and controlling, during the processingstep, temperature of the carcass with at least one of a group consistingof gas and a mixture of water and ozone.

In one aspect of the invention, the gas includes ozone and is sprayed onthe carcass to cool the carcass cryogenically.

In another aspect, the mixture of ozone and water is sprayed on thecarcass to cool the carcass.

In another aspect, the sprayed water is collected, purified, and reusedduring processing.

In another aspect, temperature is sensed in the processing area and coldgas is flowed into atmosphere of the processing area when the sensedtemperature is above a predetermined amount.

In another aspect, cold gas passes through a passage arranged in a wallof the processing area so that the cold gas flows through the passage toremove heat from the processing area through the wall.

In still another aspect, food is frozen in a freezer by spraying thefood with a cryogenic gas, the gas sprayed in the freezer is collected,and the carcass is cooled during the processing step with the collectedgas.

In an additional aspect, the amount of a predetermined gas is sensed andthe predetermined gas is added into the processing area based on thesensed amount.

Additionally, the present invention includes a system comprising wallsforming a partially enclosed room having an entrance and exit, aconveyor for conveying an animal carcass from the entrance to processingequipment positioned in the room, gas supply lines communicating withthe room, the gas supply lines being coupled to gas sources, at leastone sensor for sensing at least one of the amount of a predeterminedtypes of gases in the room and the temperature in the room, and acontroller for regulating flow of gas in the supply lines according toat least one of the sensed amount and the temperature so that microbialgrowth in the room is reduced.

In another aspect, the animal carcass is sprayed, while it is beingprocessed, with a mixture of ozone and water to reduce microbial growthon the carcass.

In yet another aspect, microbes are reduced during animal slaughter byintroducing into the slaughter area a mixture of gases including ozoneand at least one of the group consisting of nitrogen, argon, and carbondioxide so that the mixture of gases kills the animal and reduces theamount of microbes on the animal.

In still another aspect, gas is sprayed within a cavity of the carcassto reduce microbial growth and cool the carcass.

Further, the invention includes a conduit sized for insertion into ananimal carcass, first and second sprayers for coupling to a source of amixture of ozone gas and water, and a shield for shielding the carcassfrom contact with substances sprayed off of the conduit.

In an additional aspect, ultrasonic oscillations are emitted in achilled bath of ozone and water to loosen microbes from an exteriorsurface of the animal carcass.

In another aspect, an exterior surface of an animal carcass is heated toopen pores and trisodium phosphate is sprayed on the carcass while thepores are open.

In still another aspect, feathers are removed from the exterior of afowl carcass and the carcass is sprayed with at least one of an ozoneand water mixture and trisodium phosphate.

In a further aspect, a live animal is washed with a mixture of ozone andwater.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, and are intended toprovide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention. In the drawings,

FIG. 1 is a schematic view of a preferred embodiment of the foodprocessing system and includes lines representing gas flows in thesystem;

FIG. 2 is a partially schematic view of an interior of processing areasshown in FIG. 1;

FIG. 3 is a cross sectional view taken along line 3—3 of FIG. 2 andshows passages in a wall of the processing areas;

FIG. 4 is a schematic view of a water purifier used with the processingsystem of FIG. 1;

FIG. 5 is another schematic view of the food processing system of FIG. 1and includes lines representing water flow in the system;

FIG. 6 is a partial view of a washer used in one or more of theprocessing areas shown in FIG. 1;

FIG. 7 is a partial view of a feather remover used in one of theprocessing areas shown in FIG. 1;

FIG. 8 is a partially schematic view of a conduit, shield, and sprayersfor processing a chicken carcass in one of the processing areas shown inFIG. 1;

FIG. 9 is a cross section of the conduit taken along line 9—9 of FIG. 8;and

FIG. 10 is a partial view of a chiller used in one of the processingareas shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the present preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings.

In accordance with the invention, a system is provided for processinglive animals into food. As embodied in FIG. 1, the system includes aplurality of processing areas 10 a-10 j in which individual tasks areperformed during food processing. Each of the processing areas 10 a-10 jis a room or chamber containing equipment associated with processinganimals into food, and adjacent pairs of the processing areas 10 a-10 jare interconnected so that the processing areas 10 a-10 j form anelongated tunnel structure.

As described in more detail below, live animals are washed in theprocessing area 10 a and slaughtered in the processing area lob. Theresulting carcasses are then conveyed through processing areas 10 c-10 jwhere they are processed into food. In at least some of the processingareas 10 a-10 j, the interior atmosphere, temperature, and amount ofmicrobes are controlled during processing to reduce microbial growth andprolong shelf life of the processed food.

As shown in FIG. 1, a cryogenic freezer 20 is provided to freeze foodafter it is processed in the processing areas 10 a-10 j. The cryogenicfreezer 20 includes nozzles 22 a and 22 b respectively coupled to asource 30 a of compressed nitrogen gas and a source 30 b of compressedcarbon dioxide-gas. The nozzles 22 a and 22 b respectively spray foodwith the nitrogen and carbon dioxide gases, and, as these gases expandand cool, they absorb heat to freeze the food in the cryogenic freezer20.

Individuals of ordinary skill in the art will recognize that manydifferent types of cryogenic gases may be sprayed in the cryogenicfreezer 20 and many different types of cryogenic freezers may be used.For example, one of the nozzles 22 a and 22 b could spray compressedair, argon, oxygen, or a mixture including nitrogen, carbon dioxide,and/or compressed air. In preferred embodiments, the cryogenic freezer20 is a tunnel freezer having nozzles for spraying a cryogen on foodconveyed on a conveyor belt, a spiral freezer having nozzles forspraying cryogen on food conveyed on a spiral conveyor, a fluidized bedconveyer having nozzles for creating a fluidized bed of food andcryogen, or a cooler having nozzles for spraying a cryogen on foodconveyed on a turntable.

Although the cryogenic freezer 20 includes nozzles 22 a and 22 b in thepreferred embodiments, other configurations without nozzles arepossible. For example, the cryogenic freezer 20 could be an immersionfreezer having a conveyor for moving food through a bath of cryogen.

Vents 24 a and 24 b respectively collect nitrogen gas, carbon dioxidegas, and any other cryogenic gases, such as air, after they are sprayedin the cryogenic freezer 20. At the time these gases are collected, theyare still extremely cold. For example, the temperature of the gases maybe approximately —50° F. (—45.6° C.).

In contrast to conventional freezing processes in which cold cryogenicgases are released into the atmosphere after being sprayed, the systemof the present invention reuses or “recycles” the cold gases after theyare collected. As explained in more detail below, the collected gasesare used to cool food and/or asphyxiate microbes during food processingto reduce thereby microbial growth.

After the vents 24 a and 24 b collect the cold gases such as nitrogenand carbon dioxide, these cold gases are directed separately to acontroller 40 coupled to the cryogenic freezer 20. Nitrogen and carbondioxide also flow to the controller 40 directly from the source 30 a ofcompressed nitrogen gas and the source 30 b of compressed carbon dioxidegas. Other gas sources may also be connected to the controller 40. Forexample, the controller 40 may be connected to a source of oxygen, asource of argon, and/or a source including a mixture of at least some ofthe following gases: nitrogen, carbon dioxide, oxygen, argon, and ozone.

As shown in FIG. 1, the controller 40 is also preferably connected to asource 30 c of ozone gas. The ozone gas source 30 c is preferably anozone generator capable of converting substances such as pure oxygen,air, or water into ozone gas. For example, the ozone gas source 30 c mayinclude an ultraviolet light source for generating ozone. Optionally,the ozone flowing to the controller 40 from the source 30 c is mixedwith oxygen if the ozone generator does not convert all of the inputoxygen into ozone or if some of the generated ozone changes to oxygen.The ozone flowing to the controller may also be mixed with air when airis input to the ozone generator and the air is not completely convertedto ozone.

In the controller 40, nitrogen collected by vent 24 a is blended withnitrogen flowing directly from nitrogen source 30 a, and carbon dioxidecollected by vent 24 b is blended with carbon dioxide flowing directlyfrom source 30 b. The controller 40 controls flow of blended nitrogen,blended carbon dioxide, ozone, and any other gases to the processingareas 10 a-10 j and to a storage area 50, shown in FIG. 1 and describedin more detail below. Because some of the nitrogen, carbon dioxideand/or other gases may originate from the cryogenic freezer 20, thenitrogen, carbon dioxide, and/or other gases directed to the processingareas 10 a-10 j and storage area 50 are cold enough to cool animalcarcasses processed in the processing areas 10 a-10 j and cool foodstored in storage area 50. In addition, the nitrogen, carbon dioxide,ozone, and other gases preferably flow into atmosphere within theprocessing areas 10 a-10 j and storage area 50 to reduce microbialgrowth.

The controller 40 controls the relative amounts of each of the gasesbeing blended and each of the gases flowing to each of the processingareas 10 a-10 j and the storage area 50. Although the controller 40preferably blends the respective cold gases collected at the vents 24 aand 24 b with gases from the sources 30 a and 30 b, the controller 40 iscapable of flowing gases from the vents 24 a and 24 b or from thesources 30 a and 30 b without blending them.

In the storage area 50, the cold nitrogen, cold carbon dioxide, ozone,and other gases flowing from the controller 40 are released intoatmosphere surrounding food products stored in the storage area 50. Thecontroller 40 regulates the concentrations of gases and temperature inthe storage area 50 by controlling the respective amounts of gasesflowing to the storage area 50. This extends the storage life of thefood products, as compared to conventional cold storage systems, becausethe nitrogen, carbon dioxide, and ozone control microbial growth andmaintain a cooled environment in the storage area 50. In addition, thestorage area 50 costs much less to operate because it uses coldnitrogen, cold carbon dioxide, and other gases collected at vents 24 aand 24 b that would have otherwise been released into the environmentand wasted.

FIG. 2 shows the general layout of each of the processing areas 10 a-10j. As shown in this figure, each of the processing areas 10 a-10 jincludes walls 100 forming a partially enclosed room having an entrance102, an exit 104, and an interior 116. Preferably, the correspondingexit 102 and entrance 104 of adjacent pairs of the processing areas 10a-10 j are joined to one another to form the tunnel-shaped configurationshown in FIG. 1.

As shown schematically in FIG. 2, each of the processing areas 10 a-10 jpreferably includes processing equipment 106 for performing a step orsteps associated with processing a live animal into food. For example,the processing equipment 106 may include an animal washer, an animalhead capture device, gas nozzles for spraying an animal withslaughtering gas, a neck slitting device, blood removal drains, ascalding tank, a feather remover, a hide remover, a hair removingdevice, a viscera remover, a cutting device, a chiller, transportingequipment, or packager, such as a high speed atmosphere controlledpackaging device.

A conveyor 108 preferably conveys live animals and/or animal carcassesthrough each of the processing areas 10 a-10 j by moving them from theentrance 102 to the processing equipment 106, and then to the exit 104.Each one of the processing areas 10 a-10 j may include a separateconveyor 108, or adjacent processing areas may have a common conveyor108. As shown in FIG. 2, the conveyor 108 is preferably an overheadchain driven conveyor having shackles 108 a for supporting animalcarcasses. Other conveying arrangements, however, may be used withoutdeparting from the scope of the invention. For example, the conveyor 108may be a moving belt positioned below the processing equipment 106 or itmay be a channel containing moving water for floating animal carcassesalong a path.

As shown in FIG. 2, each of the processing areas 10 a-10 j includes aprocessing area controller 110 receiving input of ozone, nitrogen, andcarbon dioxide gases from the controller 40 shown in FIG. 1. Supplylines 112 a, 112 b, and 112 b respectively supply ozone, nitrogen, andcarbon dioxide from the processing area controller 110 to inlets 1142 a,1142 b, and 1142 c communicating with the processing area interior 116.Each of the inlets 1142 a, 1142 b, and 1142 c includes a blower fan 118for forcing the gases into the processing area interior 116 and amovable door 120 for closing the inlets 1142 a, 1142 b, 1142 c when theprocessing area interior 116 is cleaned.

The processing area controller 110 is coupled to a sensing unit 122communicating with sensors 124 a, 124 b, 124 c, and 124 d forrespectively sensing amounts of ozone gas, nitrogen gas, and carbondioxide gas and the temperature in the processing area interior 116. Theprocessing area controller 110 respectively adds ozone gas optionally inan oxygen and/ or air gas stream, nitrogen gas, and carbon dioxide gasto the processing area interior 116 via the supply lines 112 a-112 cwhen the respective amounts sensed by the sensors 124 a-124 c are lessthan predetermined amounts sufficient to limit microbial growth. In thismanner, the amounts of gases in the atmosphere of the processing areainterior 116 are controlled to limit or reduce microbial growth in theprocessing area interior 116.

The controller 110 preferably maintains the atmosphere of the processingarea interior 116 with an amount of ozone, an amount of nitrogen, anamount of carbon dioxide, and a remainder of other gases, such as oxygenor air. For example, the gases flowing into the processing area interiorinclude nitrogen, carbon dioxide, and a mixture containing about 0.5% byweight to about 4% by weight of ozone and a remainder of oxygen or air.

Preferably, the atmosphere in the processing area interior 116 includesabout 2% by weight to about 7% by weight of ozone. When poultry, pork,or beef is processed, the processing area interior 116 preferably hasabout 3.5% by weight of ozone. When seafood is processed, the processingarea interior 116 preferably has above about 3.5% of ozone to providebleaching. In the preferred embodiment, the ozone gas flowing into theprocessing area 116 is mixed with either oxygen or air because mostozone generators do not convert all input oxygen or air into ozone.However, the total amount of oxygen and/or air in the processing area116 is preferably insufficient to allow for significant microbialgrowth.

The processing area controller 110 also adds gases to the processingarea interior 116 via the supply lines 112 a-112 c when the temperaturesensed by the temperature sensor 124 d is above a predeterminedtemperature, such as about 33° F. (0.6° C.) to about 40° F. (4.4° C.),which is sufficient to support some microbial growth. Preferably theprocessing area interior 116 is maintained at about 33° F. to providemaximum microbial growth reduction without freezing any water present inthe processing area interior 116.

In addition to reducing or eliminating microbial growth, the gasesflowing into the processing area interior 116, such as the cold gasesoriginally collected by the vents 24 a and 24 b, cool the processingarea interior 116 and animal carcasses being processed therein. Thiscooling also limits or reduces microbial growth in the processing areainterior 116.

As will be recognized by those of ordinary skill in the art other gasesmay be flowed into the processing area interior 116 in response to asensed temperature or a sensed gas amount. For example, oxygen, argon ora mixture including at least some of the following gases: ozone,nitrogen, carbon dioxide, oxygen, and/ or argon could be added to theprocessing area interior 116. When air or other gases are used to freezefood cryogenically in freezer 20, these gases can be collected andreused to perform cooling in the processing area interior 116.

As shown in FIG. 2, a nozzle 126 is positioned in the processing areainterior 116 to spray a previously compressed gas on the animalcarcasses and, optionally, on the processing equipment 106. The gasessprayed from the nozzle 126 are preferably supplied by the processingarea controller 110 and the controller 40. The sprayed gas preferablyincludes ozone, carbon dioxide, nitrogen, and/or a mixture of ozone andat least one of the following gases: nitrogen, carbon dioxide, oxygen,argon, and air.

As the gas is sprayed from the nozzle 126, it expands to cool thecarcass cryogenically and thereby reduce microbial amounts on thecarcass. In addition, the gas preferably asphyxiates microbes to provideadditional reduction in microbial amount.

Also positioned in the processing area interior 116 is a sprayer 128coupled to a source of a mixture of ozone and water. The sprayer 128sprays a stream, aerosol, or mist of the ozone and water mixture on thecarcass and, optionally, on the processing equipment 106 to washsubstances from the carcass and processing equipment 106. After theozone and water mixture is sprayed, the mixture and any substancescarried by the mixture are drained in a drain 129 positioned in a bottomportion of the processing area interior 116. As described in more detailbelow, the system purifies the water of the drained mixture andrecombines it with more ozone to form the ozone and water mixturesprayed by the sprayer 128.

The sprayed zone and water mixture preferably includes at least about0.00002% by weight of ozone and up to about 0.0018% by weight of ozone.The ozone in the mixture limits or reduces microbial growth on thecarcass and equipment 106 to limit or prevent contamination betweendifferent carcasses.

Preferably, the water and ozone mixture is chilled to a temperature offrom about 33° F. (0.6° C.) to about 40° F. (4.4° C.) so that themixture sprayed from the sprayer 128 cools the carcass while it is beingprocessed. This cooling also reduces the amount of microbes on thecarcass.

Because excessive amounts of the processing area gases, such as ozone,are toxic to humans, the walls 100 isolate the atmosphere in processingarea interior 116 from workers to maintain human safety. This is incontrast to conventional food processing facilities where workers arepresent in the immediate vicinity of food processing equipment.

Preferably, the walls 100 of each of the processing areas 10 a-10 j aresealed to prevent leakage of gases from anywhere other than the entrance102 and exit 104 of the processing area interior 116. When the gasespass into the entrance 102 and exit 104, negative pressure exhaustpassages 130 positioned in the entrance 102 and exit 104 remove thegases so that they do not pass into other areas of the food processingsystem. To destroy potentially toxic amounts of ozone gas, each of theexhaust passages 130 optionally includes an ozone gas scrubber 132, suchas a manganese dioxide filter.

When the gases removed by the negative pressure exhaust passages 130have not been heated significantly, the system preferably recycles thesegases for reuse in the processing areas 10 a-10 j. This recycling isperformed by directing the collected gases from the exhaust passages 130to the processing area controller 110 when the gases are below apredetermined temperature, such as about —50° F. (—45.6° C.) to about 0°F. (—17.8° C.). The processing area controller 110 then distributesthese recycled gases to one of the supply lines 112 a-112 c or thenozzle 126. This gas recycling reduces the amounts of gases required toperform cooling and thereby increases the cooling efficiency of thesystem.

After the ozone and water mixture is sprayed from the sprayer 128, someof the ozone gas may come out of the mixture and be released into theprocessing area interior 116. Preferably, this ozone is collected by theexhaust passages 130 and reused during food processing. In thealternative, this collected ozone gas is scrubbed from the gasesexhausted from the processing area interior 116 when the ozone gasscrubber 132 is present.

As shown in FIG. 2, emitters 134, such as ultrasonic oscillators orspeakers, are preferably positioned in the processing cells 10 a-10 j.The emitters 134 emit ultrasonic vibrations or oscillations in theprocessing cell interior 116 to loosen microbes from exterior surfacesof the carcasses and processing equipment 106. To remove a significantnumber of microbes, the emitters 134 preferably emit the ultrasonicvibrations while the ozone and water mixture is sprayed from sprayer128. For example, the frequency of the ultrasonic oscillations may beabout 100.6 kHz to about 848.2 kHz, or below or above this range.

As shown in FIG. 3, the walls 100 of the processing areas 10 a-10 jinclude internal passages 134. These internal passages 134 are incommunication with the gases flowing from processing area controller 110so that the walls 100 form a heat exchanger for removing heat from theprocessing area interior 116. In response to an increased temperaturebeing sensed by the temperature sensor 124 d, the processing areacontroller 110 sends to the internal passages 134 cold gases, such asthe cold nitrogen and/or carbon dioxide gases collected by the vents 24a and 24 b. The cold gases flow in the internal passages 134 and act asa heat exchange medium to remove heat from the processing cell interior116 through the portion of the wall 100 facing the processing cellinterior 116. After the gases flow through the internal passages 134 andabsorb heat, they are either vented into the environment or directedback to the processing area controller 110 for reuse.

The food processing system cools a carcass in at least four differentways during food processing: 1) by flowing gases into the processingarea 116 through the inlets 114 a-114 c, 2) by spraying gases directlyon the carcass from the nozzle 126, 3) by spraying the ozone and watermixture on the carcass from the sprayer 128, and 4) by directing gasesthrough the internal passages 134. Preferably, the gases used to performthe cooling of 1), 2), and 4) include the gases collected by the vents24 a and 24 b from the cryogenic freezer 20.

In contrast to conventional food processing system in which a carcass iscooled only at the end of a processing line, the present invention coolsan animal carcass as soon as it is practical and as much as possibleduring processing to maximize shelf life and reduce microbial growth. Inparticular, the food processing system preferably cools the animalcarcass immediately after it is slaughtered and drained of blood,because blood drainage may be hindered by reduced temperatures.Preferably, the food processing system continues this cooling up to andincluding the time when the carcass is processed further and packaged.To maximize cooling efficiency in some instances where the animalcarcass is heated during food processing, for example, to loosenfeathers or remove a hide, the carcass cooling is initiated afterheating rather than immediately after slaughter and blood drainage.

Because the ozone and water mixture and gases, such as ozone, carbondioxide, and nitrogen, are used for cooling, rather than pure water, thepresent invention requires less water than conventional food processingsystems. The preferred embodiment of the invention uses a reduced amountof fresh water and produces a reduced amount of waste water by purifyingand recycling water used by the system.

Preferably, the system includes a water purifier 200, shown in FIG. 4,for converting water used in the cells 10 a-10 j into potable form.Water, previously used in the cells 10 a-10 j, is drained through thedrain 129, shown in FIG. 2, and flows through a filter 210 that removessolid particles suspended in the water so that the light transmissivityof the water is at least 80 nanometric turbity units (NTU). The filter210 may be any type of conventional device for filtering solids, suchas, for example, those disclosed in U.S. Pat. Nos. 5,322,623; 5,318,708;and 5,262,047, the disclosures of which are incorporated herein byreference.

After passing through the filter 210, the purifier 200 removes dissolvedsolids in the water by passing the water through one or more of thefollowing conventional water purification devices: an inlineelectrocoagulation device 212 that sends a DC current through the waterto drive particles, such as organic material, from the water; an inlineozone injector 214 that injects ozone into the water to increase theoxygen level of the water and correspondingly reduce the biologicaloxygen demand of the water; an ozo-flotation device 216 that cleanses,purifies, deodorizes, and stabilizes the water by bubbling ozone throughthe water to disturb the polar balance between particles and float theparticles to the top of a tank where a paddle removes them; and abiofiltration device 218 including an activated carbon filter havingspecial bacteria grown thereon to reduce contaminants and carcinogens byconverting them into acid.

The purifier 200 then purifies the water further by exposing the waterto ultraviolet light emitted from an ultraviolet light source 220 andadding 2-4 ppm chlorine from a chlorine source 222. The resulting wateris preferably potable and can therefore be reused by the system.Preferably, the purified water has a total plate count of less than 500colony forming units per milliliter (CFU/ml), no coliform or E. coli,total organic carbon of less than 100 mg/l, and a percent lighttransmittance where less than 5 of each water sample has no more than 1NTU and none of the water is greater than 5 NTU.

FIG. 5 is a water flow diagram for the food processing system. As shownin FIG. 5, fresh water from a fresh water source 230 enters the foodprocessing system. A blending device 240 automatically combines thefresh water from the fresh water source 230 with reconditioned potablewater (RPW), which has been purified by the purifier 200, to createcomplex feed water (CFW).

Preferably, a total organic carbon detector 242 measures the amount oftotal organic carbon in the RPW before the RPW flows into the blendingdevice 240. In response to signals from the total organic carbondetector 242, the blending device 240 automatically adds fresh water tothe RPW when the sensed amount of total organic carbon rises above amaximum level, such as, for example, 100 mg/l. Preferably, the blendingdevice 240 continuously blends a sufficient amount of fresh water withthe RPW to regulate the amount of total organic carbon in the resultingCFW.

The CFW flows to the processing areas 10 a-10 j where it is combinedwith ozone, such as the ozone from source 30 c shown in FIG. 1, andsprayed, for example, by sprayer 128 on animal carcasses and processingequipment 106. As explained above, the ozone and water mixture is usedto cool the animal carcass, reduce microbial growth on both theprocessing equipment 106 and carcass, and wash substances from both thecarcass and processing equipment 106. After performing these functions,the water and ozone mixture is drained from the processing areas 10 a-10j and carries washed substances along with it.

The purifier 200, described above, then removes particles from the waterand the purified water (RPW) renters the blending device 240 for reuse.As shown in FIG. 5, the purifier 200 may include an ozone monitor 244that determines the oxidation reduction potential of the water, andlight transmission monitors 246 that measure the turbidity of the water.Preferably, some or all of the devices 210-222 of the purifier 200 actin response to the monitors 244 and 246 to reduce amounts ofcontaminants in the water passing from processing areas 10 a-10 j.

Because the system purifies water used during food processing and reusesthe water, the amount of fresh water required by the food processingsystem is significantly reduced from that required by conventionalsystems. For example, when the system is used to process poultry, thesystem reuses about 90% of the water and requires significantly lessfresh water than conventional food processing systems. In conventionalpoultry processing, about 7 to 10 gallons (26.5 to 37.9 liters) of freshwater is required for each chicken that is processed. When the presentinvention is used for poultry processing, it preferably uses only about0.75 gallons (2.8 liters) to about 1 gallon (3.8 liters) of fresh water.The resulting fresh water savings significantly reduces food processingcost and allows for food processing in geographic areas having a limitedsupply of fresh water.

If a processing area, such as processing area 10 k, shown in FIG. 5,requires fresh water that has not been blended with recycled water, thefood processing system directs fresh water from the fresh water source230 directly to the processing area 10 k without blending it with theRPW.

Some of the processing areas, such as a processing area 10L, may add tothe CFW substances, such as large amounts of fecal matter or salt, thatare difficult to remove completely and may contaminate or “damage” theRPW. Water flowing from the cell 10L is preferably filtered by aparticle filter 250 like the filter 210 and chlorinated with chlorinefrom a secondary chlorine source 252 to create limited reuse water (LRW)that is stored in LRW storage 254. Rather than being used in theprocessing areas 10 a-10 j during food processing, the LRW stored in LRWstorage 254 is preferably used in areas of the system that do notrequire potable water, such as a cooling tower, a vacuum device, ananimal pen wash device, a truck washing area, or a soil cleaning device(not shown).

Methods of processing live chickens into food with the structure shownin FIGS. 1-5 and additional structure shown in FIGS. 6-10 are discussedbelow. Although the invention is described in association with poultryprocessing, it should be understood that the invention in its broadestaspects is not so limited. For example, the invention may be readilypracticed to process many different types of animals such as cattle,swine, sheep, lamb, ostrich, seafood including fish, or types of fowlother than chickens, such as turkeys and ducks. In addition, the methodof the invention in its broadest sense could be practiced with structuredifferent from that described in connection the embodiments shown inFIGS. 1-10.

To process chickens into food, live chickens are delivered to the foodprocessing system and workers place the chickens in the shackles 108 aof the conveyor 108. Initially, the conveyor 108 moves the live chickensthrough processing area 10 a, which includes a washer 300, shown in FIG.6. The washer 300 has a plurality of sprayers 302 coupled to a source ofthe ozone and water mixture that is pressurized at a pressure of fromabout 1,200 pounds per square inch (8,273,708 N/m²) to about 2,000pounds per square inch (13,789,514 N/m²⁾. The ozone and water mixturepreferable includes at least about 0.00002% by weight of ozone and up toabout 0.0018% by weight of ozone.

The sprayers 302 are preferably positioned so that they spray themixture at particular areas of the live chickens, such as the rear end,to wash soil, filth, and fecal matter from each of the chickens. This isin contrast to conventional food processing methods in which liveanimals are not washed prior to being processed.

In addition to the sprayers 302, the washer 300 includes brushes 304 forscrubbing the chickens being conveyed by the conveyor 108, and nozzles306 for spraying the chickens with a gas mixture including from about 1%to about 5% by weight of ozone. The ozone in the mixtures sprayedrespectively from the sprayers 302 and nozzles 306 significantly reducesmicrobial growth and the amount of microbes on the chickens.

After the chickens are washed in the processing area 10 a, the conveyor108 conveys the chickens to the processing area 10 b. The atmosphere inthe processing cell 10 b includes ozone in combination with a gasmixture of nitrogen and/or argon, optionally some carbon dioxide, and asmall amount of oxygen or air. Preferably, the processing cellatmosphere includes ozone combined with the nitrogen, argon, carbondioxide, and/or oxygen gas mixtures disclosed in European PatentApplication Publication No. 0 434 278 A1, published on Jun. 26, 1991.

For example, the atmosphere in the processing cell/ 10 d may includefrom about 0.0007% by weight to about 0.0018% by weight of ozone. Theremainder of the atmosphere includes at least about 98% by weight ofnitrogen, argon, carbon dioxide, and a remainder of oxygen. As thechickens breathe these gases, they are stunned and almost instantlyslaughtered to produce a carcass without significant suffering.

During the slaughter, the chickens become exposed to the ozone blendedin the processing cell atmosphere so that microbial growth on theexterior surface of the chickens is reduced even further. This issignificant because most, if not all, known gas slaughtering processesdo not employ a gas or other means for reducing pathogen growth on aresulting animal carcass.

Although gases are preferably used to slaughter the chickens inprocessing area 10 d, other slaughtering or stunning processes may beused. For example, the chickens may be stunned with a conventionaldevice (not shown) that sends an electrical pulse through each chicken.

As the processing continues, the chicken carcasses are conveyed into theprocessing areas 10 c and 10 d, where the necks of the chicken carcassesare severed and blood is allowed to drain from the carcasses,respectively. In processing areas 10 c and 10 d, nozzles and sprayers,such as nozzle 126 and sprayer 128 shown in FIG. 2, preferably sprayozone and the mixture of ozone and water directly at each of the chickencarcasses to reduces the amount of microbes during neck severing andblood drainage. Optionally, the processing areas 10 c and 10 d alsoinclude the washer 300 shown in FIG. 6.

The conveyor 108 then transports the chicken carcasses to a scaldingdevice (not shown) positioned in processing cell 10 e. Each of thechicken carcasses is dipped into heated liquid contained in the scaldingdevice to loosen feathers from the exterior surface of the carcasses.For example, the scalding device may be configured like the scaldingsystem disclosed in U.S. Pat. No. 4,996,741, which is incorporatedherein by reference.

After scalding, the conveyor 108 moves the chicken carcasses through theprocessing areas 10 f-10 j, where the ozone and water mixture and thegases, such as ozone and/or the gases collected by the vents 24 a and 24b of the cryogenic freezer 20, preferably cool the chicken carcasses forthe remainder of the processing. As described above in connection withthe description of the processing area interior 116 shown in FIG. 2,cooling is performed by spraying the ozone and water mixture from thesprayer 128 in a stream, aerosol, or mist directly on the carcasses,spraying gas from the nozzle 126 directly on the carcasses, directinggas through inlets 1142 a-1142 c into the processing cell interior 116,and/or flowing the gas through the interior passages 134 in walls 100.

The chicken carcasses are preferably cooled immediately after scaldingbecause the cooling would be inefficient if it took place prior thereto.A carcass chiller, such as carcass chiller 600 shown in FIG. 10 anddescribed in more detail below, is preferably used to perform thiscooling rapidly. Cooling the chicken carcasses prior to feather removalloosens feathers from the carcass and closes pores in the carcass skinthereby reducing the likelihood of trapping microorganisms in the pores.If the chicken carcasses are not scalded to loosen feathers, the coolingis initiated immediately after blood is drained from the carcasses. Inthe alternative, the cooling could be initiated immediately afterslaughter if this does not hinder blood drainage.

The processing area 10 f includes at least one feather remover 400 shownin FIG. 7. The feather remover 400 includes a support 410 coupled to amotor (not shown) so that the support 410 and a plurality of tines 420mounted to the support 310 rotate, for example, about an axis of thesupport 410 in a direction A.

Each of the tines 420 includes a first lumen in fluid communication witha source of the of ozone and water mixture, and a second lumen in fluidcommunication with a source of trisodium phosphate. The first and secondlumens have respective openings 422 a and 422 b for spraying the ozoneand water mixture and the trisodium phosphate on chicken carcassesduring feather removal.

As chicken carcasses are conveyed through the processing area 10 e, thesupport 410 rotates so that the tines 420 come in contact with the outersurface of the chicken carcasses and remove feathers therefrom. Whilethe feathers are being removed, the ozone and water mixture andtrisodium phosphate are sprayed from the openings 422 a and 422 b,respectively. In addition, ultrasonic oscillations are preferablyemitted from the emitters 134 shown in FIG. 2.

Because the chicken carcasses enter the processing area 10 f after beingscalded in the processing area 10 e, pores in the exterior surface ofeach of the chicken carcasses are open. The trisodium phosphate sprayedfrom openings 422 b is forced into these open pores and renders theexterior surface of the chicken carcasses extremely slippery. This makesit difficult for bacteria and other microbes to attach to the slipperyexterior of the chicken carcasses as the ozone and water is sprayed fromthe openings 422 a to wash microbes from the carcasses.

The ultrasonic oscillations generated by the emitters 134 loosen thebacteria and other microbes from the chicken carcasses. This alsoassists in removing bacteria and other microbes from the exterior of thechicken carcasses as the chicken carcasses are sprayed with the ozoneand water mixture.

Although the feathers are preferably removed when the tines 420 contactthe outer surface of the chicken carcasses, the feathers could beremoved in other ways. For example, the ozone and water mixture and/ortrisodium phosphate sprayed from the tines 420 could remove the featherswithout having the tines 420 themselves come in contact with thecarcass. In addition, the ultrasonic oscillations emitted from theemitters 134 could remove feathers.

After the feathers are removed in the processing area 10 f, the conveyor108 moves the chicken carcasses into processing area 10 g, whereprocessing equipment 106 removes viscera from the conveyed chickencarcasses. For example, the processing equipment 106 for removingviscera preferably includes croppers, neck breakers, head pullers,venters, openers, eviscerators, inside/outside bird washers, and/or lungremoval vacuums.

To cool the chicken carcasses and reduce microbial growth after visceraremoval, a conduit 500, shown in FIGS. 8 and 9, is inserted into aninternal cavity of the carcasses and substances, such as nitrogen gas,carbon dioxide gas, ozone gas, and/or a mixture of ozone and water, aresprayed from the conduit 500 into the cavity. As shown in FIGS. 8 and 9,the conduit 500 includes a plurality of lumens 502 a, 502 b, and 502 ccoupled to sources of the substances and a plurality of apertures 504 a,504 b, and 504 c respectively communicating with the lumens 502 a-502 cto spray the substances therefrom.

As the conduit 500 enters the cavity of a chicken carcass, a shield 512,shown in FIG. 8, is moved toward the conduit 500 so that the conduit 500is positioned within a slot 514 in the shield 512. The shield 512 coversan opening in the chicken carcass to partially trap gases being sprayedin the cavity of the carcass. The sprayed gases, such as nitrogen,carbon dioxide, and/ or ozone, preferably fill the cavity and purge anyoxygen residing in the cavity. This is significant because many microbesare unable to survive in the absence of oxygen.

Sprayers 520 are positioned to spray the ozone and water mixture on theexterior of the chicken carcass and the exterior surface of the conduit500 as the conduit 500 is removed from the cavity. Preferably, theemitters 134, shown in FIG. 2, emit ultrasonic oscillations while theozone and water mixture is sprayed to loosen microbes from the chickencarcasses.

The sprayed ozone and water mixture reduces microbial growth andprevents cross contamination between chicken carcasses as the conduit500 is inserted from one chicken carcass into another. To shield thechicken carcass from any substances sprayed off of the conduit 500, theshield 512 covers the chicken carcass while the sprayers 520 spray theozone and water mixture.

The chicken carcasses are conveyed from the processing area 10 g intoprocessing area 10 h. The processing area 10 h includes a carcasschiller 600, shown in FIG. 10, containing chilled ozonated water. Thecarcass chiller 600 is preferably constructed like the carcass chillerand sterilizer disclosed in U.S. Pat. No. 4,827,727, which isincorporated herein by reference. Because the chicken carcasses arecooled in each of the processing areas 10 f through 10 h, the size ofthe carcass chiller 600 may be smaller than that required inconventional chicken processing to chill a carcass to a predeterminedtemperature.

As shown in FIG. 10, the carcass chiller 600 preferably includesultrasonic emitters 610, similar or identical to the emitters 134 shownin FIG. 2. Each of the chicken carcasses are dipped in the carcasschiller 600 as the conveyor 108 moves them through the processing area10 h so that the chilled ozonated water in the carcass chiller 600surrounds the carcasses. When the carcasses are in the ozonated water,ultrasonic oscillations emitted from emitters 610 dislodge bacteria andother microbes trapped in the pores of the chicken carcasses so that theozone in the ozonated water destroys them.

Optionally, the processing area 10 h also includes an additionalozonated water bath (not shown) for contacting an external surface ofthe chicken carcass with ozonated water while the carcasses aresubmerged. For example, the poultry carcasses may be exposed to ozonatedwater in the manner described in U.S. Pat. Nos. 4,849,237 and 5,227,184,the disclosures of which are incorporated herein by reference.

If the chicken carcass is to be cut into portions before it is packaged,the chicken carcass is conveyed by the conveyor 108 into the processingarea 10 i. In the processing area 10 i, cutting implements (not shown)cut the chicken carcass into portions and the portions are separatedaccording to the manner in which they will be packaged. Preferably, thenozzle 128, shown in FIG. 2, sprays the cutting implements with theozone and water mixture. This reduces microbial growth and limits thepossibility of cross contamination when the cutting implements slicedifferent chicken carcasses.

If the chicken carcass is to be packaged, the conveyor 108 conveys thechicken carcass to the processing area 10 j, which includes packagingmachinery (not shown). Preferably, the chicken carcasses are packaged inmodified atmosphere packaging containing gas mixtures including ozone.These gas mixtures prolong shelf life and resist decolorization of thechicken meat. For example, the packaging machinery may package thechicken carcasses by using the controlled atmosphere packaging methodsdescribed in U.S. Pat. Nos. 4,933,411 or 5,352,467, the disclosure ofwhich are incorporated herein by reference.

The resulting packaged and unpackaged poultry food products can bestored in the storage area 50, frozen in the cryogenic freezer 20, orshipped to other locations. In addition, the unpackaged poultry productscan be processed further such as by breading or frying.

As the live chickens are processed into food, the atmosphere in each ofthe processing areas 10 a-10 j is controlled to reduce microbial growthand prolong shelf life. Because the chicken carcass is heated in thescalding tank, cooling with the gases and mixture of ozone and waterpreferably takes place only after scalding. However, when the inventionis practiced to process chicken or other animals into food withoutscalding or heating the carcass, the gas cooling may be conductedthroughout the food processing immediately after the animal isslaughtered and bled.

During poultry processing or processing of other animals, the water usedin each of the processing areas 10 a-10 j is collected and reused in theprocessing areas 10 a-10 j after it is purified to potable form by thewater purification system shown in FIG. 5. Because a substantial amountof the water is reused, =the present food processing system represent adramatic improvement over existing food processing systems.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure andmethodology of the present invention without departing from the scope orspirit of the invention. In view of the foregoing, it is intended thatthe present invention cover modifications and variations of thisinvention provided they fall within the scope of the following claimsand their equivalents.

What is claimed is:
 1. A method of reducing microbial growth duringprocessing of an animal carcass, comprising the steps of: processing ananimal carcass ; heating an exterior surface of the animal carcass toopen pores in the exterior surface of the animal carcass; and sprayingthe animal carcass with trisodium phosphate while the pores are open. 2.The method of claim 1, wherein the heating of the exterior surface ofthe carcass comprises placing heated liquid in contact with the carcass.3. The method of claim 1, further comprising removing feathers from theheated exterior surface of the carcass.
 4. The method of claim 1,further comprising spraying the carcass with a mixture of water and asubstance for reducing microbial growth on the carcass.
 5. The method ofclaim 4, further comprising collecting sprayed water, purifying thewater, and reusing the purified water during processing of animalcarcasses.
 6. The method of claim 4, wherein the substance comprisesozone.
 7. The method of claim 1, wherein the trisodium phosphate reducesadherence of microbes on the exterior surface of the carcass.
 8. Themethod of claim 1, wherein the spraying further comprises spraying waterand wherein the method further comprises collecting sprayed water,purifying the water, and reusing the purified water during theprocessing.
 9. A method of reducing microbial growth while removingfeathers from a fowl carcass, the method comprising the steps of:heating the exterior of a fowl carcass; rotating a plurality of tinesabout an axis of rotation; removing feathers from the exterior of thefowl carcass; and spraying the carcass with at least one of an ozone andwater mixture and trisodium phosphate while the feathers are beingremoved to reduce microbes on the carcass.
 10. The method of claim 9,wherein the step of spraying includes the substeps of spraying the ozoneand water mixture through a first aperture in the tines and spraying thetrisodium phosphate through a second aperture in the tines.